Disabling or dialing back notifications for various apps also helps a bunch. I'm fine with a Slack popup notification, but I don't want a sound or vibration.
So even if I got 3 text messages, 2 missed calls, and other random notifications, the bar would show only one notification, and I would not get a sound/light. You'd have to click on it to see the actual notifications you missed.
You could, of course, have whitelists to let certain notifications through.
Best. App. Ever. It's great to be able to work or do whatever for hours, knowing that your phone can't interrupt you (unless someone calls, which they rarely do).
Sadly stopped working after some Android update. I'm sure there are similar apps, though.
And if the app is good, it will categorize it's notification types in a user-centric way and allow you to enable only specific categories.